EF Code First 4.1 doesn't support nvarchar(max) at all?

Question

I've spent decent amount of time on this problem and still can't figure out why EF team makes the life so hard using Code First.

So here is some sample:

My POCO:

The way I want the thing to look like:

public class Post
{
     public int Id {get; set;}
     public string Text {get; set;}
}

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Post>()
        .Property(p => p.Text)
        .HasColumnType("nvarchar(max)");   
}

The only thing that works:

public class Post
{
     public int Id {get; set;}

     [StringLength(4000)]
     public string Text {get; set;}
}

The problem is that when in first case I try to insert anything it gives me: Validation failed for one or more entities and the second case doesn't fit my business model.

Am I the only one with this problem? How do I deal with this thing?

Andre Artus · Accepted Answer · 2017-09-06T14:41:46.420

Using Int32.MaxValue may lead to some problems when connected to a SQL Server database. Using Int32.MaxValue in either the attribute or the api throws an exception stating "String column with MaxLength greater than 4000 is not supported". But, using either of the following methods works fine for me in EF 4.1:

You can use the MaxLengthArritbute, e.g.

[MaxLength]
public string Text { get; set; }

Or the fluent API, like so

 protected override void OnModelCreating(DbModelBuilder modelBuilder)
 {
      modelBuilder.Entity<Post>()
        .Property(s => s.Text)
        .IsMaxLength();
 }

To enforce the use of ntext use one of the following:

[MaxLength]
[Column(TypeName = "ntext")]
public string Text { get; set; }

Or the fluent API, like so

 protected override void OnModelCreating(DbModelBuilder modelBuilder)
 {
      modelBuilder.Entity<Post>()
        .Property(s => s.Text)
        .HasColumnType("ntext") 
        .IsMaxLength();
 }

You may not need the MaxLength attribute in this case.

UPDATE (2017-Sep-6):

As Sebazzz pointed out in his comment ntext (and text) has been deprecated in SQL Server 2016. Here is a link to further information:

https://learn.microsoft.com/en-us/sql/database-engine/deprecated-database-engine-features-in-sql-server-2016

Please note `ntext` is deprecated. It is not advisable to use it for new development. — Sebazzz, Sep 06 '17 at 11:09

score 4 · Answer 2 · answered Mar 17 '11 at 23:01

4

Use this:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Entity<Post>()
        .Property(p => p.Text)
        .HasMaxLength(Int32.MaxValue);
}

Or this:

[StringLength(Int32.MaxValue)]
public string Text { get; set; }

answered Mar 17 '11 at 23:01

Ladislav Mrnka

360,892
59
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2

EF team should make a list of "hacks" for Code First :) – Naz Mar 17 '11 at 23:22
1

@NazarGargol: They will put one out when it's released. But they'll call it "official documentation" – Diego Mijelshon Mar 20 '11 at 20:36

score 4 · Answer 3 · answered Mar 21 '11 at 23:28

4

Using the [MaxLength] attribute without any value, as described in Andre Artus's post, works perfectly. Under SQL CE it correctly uses "ntext", while under SQL Server it uses "nvarchar(max)". This is highly desired, but should be made clearer in the documentation.

answered Mar 21 '11 at 23:28

Matt Johnson-Pint

230,703
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If you want to force `ntext` then it's easy to apply `[Column(TypeName = "ntext")]` or `.HasColumnType("ntext")` as I did in my initial post. – Andre Artus Mar 22 '11 at 20:28
2

FYI - This was changed in the final EF4.1 release. It uses nvarchar(max) by default WITHOUT using the [MaxLength] attribute. This is how it should be. :) – Matt Johnson-Pint Apr 18 '11 at 13:58
Good to know that. Looks like I'll have to poke around EF 4.1 anew. – Andre Artus Apr 18 '11 at 20:21
SQL CE 4 + EF 4.1 it uses nvarchar(4000) not ntext – Jon Davis Jul 11 '11 at 00:40

score 0 · Answer 4 · answered Feb 19 '14 at 00:58

I used the code below to get nvarchar(max) for a field in database. I am using EF5.

using System.Data.Entity.ModelConfiguration;
using Lansw.Panels.Domain.Entities;

    namespace Lansw.Panels.DataAccess.Configurations
    {
        internal class ServiceAgreementConfiguration : EntityTypeConfiguration<ServiceAgreement>
        {
            public ServiceAgreementConfiguration()
            {
                Property(t => t.ServiceAgreementText).IsRequired().IsMaxLength();
            }
        }
    }

enter image description here

score 0 · Answer 5 · answered Jul 03 '15 at 17:52

I resolved my problem with something like this:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Entity<Post>()
        .Property(p => p.Text)
        .IsMaxLength()
        .HasColumnType("nvarchar(max)");
}

EF Code First 4.1 doesn't support nvarchar(max) at all?

5 Answers5

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